Project Summary/Abstract Cryptococcus spp. represent an understudied genus of fungi that appears to have relevance to allergy and asthma. This genus has previously been understudied due to difficulties in culturing, and early-life environmental exposures are not well characterized. We propose to use high-throughput DNA sequencing to comprehensively measure exposure after birth to this fungal group. This genus is commonly found in urban environments. We will utilize house dust samples from 131 participants from an existing urban, Hispanic birth cohort at high risk of developing allergic sensitization due to heredity. The goal of this new study is to further our understanding underlying the observations of inverse associations between fungal diversity and allergic sensitization. We hypothesize that 1) beneficial housing characteristics are associated with increased Cryptococcus diversity and 2) exposure to decreased diversity within the fungal genus Cryptococcus in early-life predict allergic sensitization development among pre-school children. Aim 1 is to identify home characteristics associated with Cryptococcus exposure and temporal persistence. Aim 2 is to determine associations between exposure to Cryptococcus spp. in early-life and allergic sensitization at age 4 years. Results will represent a new paradigm for determining potentially beneficial early-life microbial exposures. Our interdisciplinary project is poised to then integrate findings into standard medical care, housing interventions and asthma programs.